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Your Gold Coast Bioretention Basin Maintenance Plan Is Part of Your Original Development Approval 

Every Bioretention basin on Gold Coast commercial properties requires maintenance to be undertaken to prevent debris buildup that can inhibit the functional operation of the inflow system, overflow pits and the subsurface drainage system. 


For same day service call (07) 5580 4311. For non-urgent repairs feel free to send us your details.

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Your Gold Coast Bioretention Basin Maintenance Plan Is Part of Your Original Development Approval

Every Bioretention basin on Gold Coast commercial properties requires maintenance to be undertaken to prevent debris buildup that can inhibit the functional operation of the inflow system, overflow pits and subsurface drainage system.

Gold Coast Bioretention Basin Maintenance & Management

At Whywait Plumbing, we are experienced in maintaining, repairing and managing bioretention basins, detention, retention basins and stormwater management systems on the Gold Coast.

Consequently, we can provide you with expert assistance for the following:

  • Ongoing cleaning, maintenance and repairs
  • Management & routine quality control checks
  • 24/7 emergency response services

The City of Gold Coast approves the maintenance plan as part of the original Development Approval or DA for every commercial development that is approved with a bioretention basin.

The correct hydraulic performance of your bioretention basins is essential to ensure the following:

  • effective stormwater treatment performance
  • to minimise damage from rainstorm overland flows
  • to protect the hydraulic integrity and function of your stormwater drainage systems

Why You Need Bioretention Basin Maintenance & Management

If your bioretention basin looks like this one in the portfolio of photos below of a bioretention basin in Yatala that we had to reconstruct completely, then you need our assistance now.

In every bioretention basin, the essential components are the surface vegetation, extended detention in the percolation process, fully functioning filter media, fully function subsurface drainage, the overflow pit allowing discharge into the main stormwater drainage system.

As the portfolio of photos below show all of these essential components were failing to function.

Bioretention Basin Maintenance

This bioretention basin in Yatala had never been maintained and was no longer draining overland flow plus was flooding surrounding properties. The sub-surface drainage system was completely blocked and failing to function completely.

Bioretention Basin Maintenance

Lack of bioretention basin maintenance in this system resulted in the failure of the entire stormwater system for the property as every part of it was silted up. Ponding of water was in every part of the system.

Bioretention Basin Maintenance

Bioretention basin maintenance is not an option as it can lead to a complete reconstruction which is what happened at this Yatala property as no part of the original system could be rectified.

Bioretention Basin Maintenance

Bioretention Basin Maintenance is not an option as it is a requirement of your Development Approval. Failure to do so here at Yatala resulted in council intervention to have the entire system completely reconstructed.

Bioretention Basin Maintenance

Bioretention Basin Maintenance is compulsory with this main pit so clogged up with silt and vegetation it needed to be completely demolished and reconstructed.

Bioretention Basin Reconstruction

Reconstruction a bioretention basin after failing to undertake the required maintenance can be an expensive exercise with excavators and bobcats required to remove and replace the filter media and relandscape.

Bioretention Basin Reconstruction

Reconstruction of a bioretention basin will always involve completely replacing all of the drainage infrastructure inclusive of pipes and pits along with connections to the main stormwater drains.

Bioretention Basin Reconstruction

Reconstructing any bioretention basin requires major attention around forebays and inflow pits to ensure they are once again 100% effective in quickly removing fast inflows during rainstorms.

Bioretention Basin Reconstruction

After the reconstruction of all of the hydraulic infrastructure, backfilling and removal of all the spoil and debris from the site the bioretention basin looks vastly different while waiting for vegetation landscaping to occur.

Council Officers can audit the maintenance of your bioretention basin at any time. Gold Coast Planning Scheme Policy 11, which is Land Development Guidelines are specified in Section 13 Water Sensitive Urban Design (WSUD) Guidelines and in Section 13.6 Bioretention Basins.

As part of the Gold Coast Development Approval, the maintenance activities must be specified in a maintenance plan along with the maintenance inspection forms. When we work on your bioretention basin, we will use this approved plan to ensure the bioretention basins continue to function as originally designed. These forms are developed on a site-specific basis as the purpose, nature, construction and configuration of every bioretention basin varies considerably.

What is a Bioretention Basin?

Bioretention Basin Integrated Into a Local Streetscape on the left and a Car Park on the right are integral requirements under Gold Coast Planning Scheme Policies

Generally, bioretention basins are vegetated areas where overland stormwater runoff is filtered through a filter media layer such as sandy loam as it percolates downwards. As it percolates down, it is then collected into slotted or perforated subsurface drains that flow to downstream pits or waterways or underground rainwater tanks for reuse.

All bioretention basins operate by filtering stormwater runoff through densely planted surface vegetation. This vegetation slows the stormwater runoff to allow the water to percolate through the sandy loam filter media. As the stormwater percolates the pollutants picked up by the overland flow of the stormwater are retained through fine filtration, adsorption and some biological uptake in the filter media.

Contrary to what ill-informed property managers and owners believe the vegetation in a bioretention system is an essential functional element of the system. The vegetation enables a substrate for biofilm growth within the upper layer of the filter media. The vegetation also facilitates the transfer of oxygen to the filter media. It enhances soil microbial communities which enhance the biological transformation of pollutants contained in the layers of filter media.

Bioretention Basin Maintenance & Management Requirements

As the vegetation plays a crucial role in maintaining the porosity of the filter media of a bioretention basin. Therefore strong healthy growth of the vegetation is essential to the performance of the bioretention basin. Intensive maintenance of the vegetation is required during the plant establishment periods when weed removal and replanting of the vegetation will be required.

The hydraulics of stormwater inflow systems and overflow pits require rigorous monitoring, as these will be prone to scouring and debris buildup, especially during the summer months when we have major storm events.

Debris buildups can easily block inlets or outlets plus can be unattractive in high visibility areas that are otherwise meticulously maintained. As part of any maintenance program inspection and removal of the debris, buildup needs to be undertaken regularly and removed from the site. If you have sediment forebays, they need to be inspected every quarter, with all of the accumulated sediment wholly removed from the site.

Typical Bioretention Basin Maintenace We Undertake

Typical maintenance of every bioretention basin we will undertake will include:

  • inspection of the bioretention basin to identify any areas of increased sediment and debris deposition
  • examination for any scouring from stormwater overland flows
  • checking for any erosion of the batters from lateral stormwater inflows,
  • inspection for any damage from vehicles and clogging of the bioretention basin
  • inspection of inflow systems
  • inspection of overflow pits and the subsurface drains to identify and clear any scouring, litter and debris buildup and blockages
  • removal of sediment where it is building up in and around the vegetation
  • inspection of the sediment forebay and removal of accumulated sediment, debris and litter
  • repairing any damage to the retention basin caused by scouring, rill erosion or vehicle damage
  • inspection of the bioretention basin surface and tilling or removal of the surface layer, if there is evidence of clogging
  • removal of invasive weeds without the use of herbicides
  • removal of any plants that have died or been vandalised and replacement with plants of equivalent size and species as detailed in the original plant schedule
  • pruning to remove any dead or diseased vegetation to stimulate growth

From experience, we have learnt maintenance should only occur after a reasonably rain-free period. This is because the filter media needs to be dry in the bioretention basin to enable us to check the subsurface drains correctly and avoid surface substrate damage.

We always recommend inspections after any significant rainstorm events so that we can check for scouring and debris buildup.

If you fail to undertake bioretention basin maintenance regularly, you risk being required by the council to reconstruct the bioretention basin entirely. Generally, this will be necessary if the bioretention basin fails to drain satisfactorily after tilling of the surface.

Bioretention Basin Maintenance Advice

For all plumbing, drainage & gas emergencies please call (07) 5580 4311 for rapid response service. For all other plumbing repairs feel free to email us for assistance.

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